'Ultrabook' is an Intel marketing term that requires a certain degree of performance and an Intel chip, not just a weight/thickness limit. You can probably find comparable AMD or lower end models advertised as thin and light.

Given most Ultrabooks are around/under 1kg, an extra kg is a doubling in weight - pretty substantial.

2.5" drives are dead and 4TB+ M.2 drives can now be bought. My biggest concern would be expandable or very large RAM.